WO2004089625A1 - Method for producing gas barrier multilayer body - Google Patents

Abstract

A method for producing a gas barrier multilayer body is disclosed which comprises formation of a multilayer body and heat-treating of the obtained multilayer body in the presence of water. The multilayer body includes a plastic base, a gas barrier layer made of a gas barrier layer-forming coating material which contains polyvinyl alcohol and ethylene-maleic acid copolymer, and a polymer layer containing a metal compound of a divalent or higher multivalent metal, and the polymer layer is put on top of at least one surface of the gas barrier layer. It is also disclosed a method for producing a gas barrier multilayer body which comprises heat-treating of a plastic base onto which a gas barrier layer-forming coating material containing polyvinyl alcohol and ethylene-maleic acid copolymer is applied directly or via an undercoat layer, and heat-treating of the thus-obtained multilayer body in the presence of water containing a metal compound of a divalent or higher multivalent metal.

Description

 Description Method for manufacturing gas barrier laminates Technical field

 The present invention relates to a method for producing a gas-parrier laminate having excellent gas barrier properties even under high humidity. Background technology

 Thermoplastic resin films such as polyamide films and polyester films are used in a wide range of applications as packaging materials because of their excellent strength, transparency, and moldability. However, these thermoplastic resin films have high gas permeability such as oxygen, so when used for packaging of general foods, retorted foods, cosmetics, medical supplies, agricultural chemicals, etc., they can penetrate the film after long-term storage. Oxidized gas such as oxygen may alter the contents.

 Therefore, a laminated film in which the surface of a thermoplastic resin is coated with polyvinylidene chloride (hereinafter abbreviated as “PVDC”) emulsion to form a PVDC layer with high gas barrier properties is used for food packaging. Has been widely used. However, since PVDC generates substances such as acid gas at the time of incineration, there is a growing interest in the environment in recent years, and there is a strong demand for the transfer to other materials.

 Polyvinyl alcohol (hereinafter abbreviated as “PVA”) as an alternative to PVDC is superior in that it does not generate toxic gas and has a high gas barrier property under low humidity atmosphere. However, as the humidity rises, its gas barrier properties decrease rapidly, so that it cannot be used for packaging of foods containing Z components in many cases.

A copolymer of vinyl alcohol and ethylene (hereinafter abbreviated as "E VOH") is known as a polymer that has improved the gas barrier property of PVA under high humidity. However, in order to maintain the gasparity at high humidity at a practical level, It is necessary to increase the copolymerization ratio of the polymer to some extent, and such a polymer becomes sparingly soluble in water. Therefore, it is necessary to use an organic solvent or a mixed solvent of water and an organic solvent in order to obtain a coating agent using EVOH, which has a high ethylene copolymerization ratio. Costs increase due to the need for processes.

 Therefore, various methods are being studied to coat a liquid composition composed of a water-soluble polymer on a film and to exhibit high gas barrier properties even under high humidity. Reference 1 (Japanese Patent Application Laid-Open No. 06-220221), Document 2 (Japanese Patent Application Laid-Open No. 07-102083), Document 3 (Japanese Patent Application Laid-Open No. 07-205379), Reference 4 (Japanese Patent Application Laid-Open No. 07-266441), Reference 5 (JP 08-041218 A), Reference 6 (JP

Japanese Patent Application Laid-Open No. 10-237180) and Document 7 (Japanese Patent Application Laid-Open No. 2000-000931) disclose techniques using a mixture of PVA and polyacrylic acid or polyacrylic acid.

 However, in the inventions proposed in the above-mentioned references 1 to 7, high-temperature heat treatment or long-time heat treatment is required to exhibit high gas barrier properties, and a large amount of energy is required during production. Environmental load is not small. In addition, heat treatment at a high temperature may cause discoloration or decomposition of the PVA or the like constituting the barrier layer, and may cause wrinkles, curling or shrinkage of the base material such as a plastic film on which the barrier layer is laminated. It becomes unusable as a packaging material due to deformation. In order to prevent the deterioration of the plastic substrate, it is necessary to use a special heat-resistant film that can withstand high-temperature heating, but this is difficult in terms of versatility and economy. On the other hand, when the heat treatment temperature is low, it is necessary to perform the treatment for a very long time, and the productivity is reduced.

Also, studies have been made to solve the above problems of the PVA film by introducing a crosslinked structure into PVA. However, generally, as the crosslink density increases, the humidity dependency of the oxygen gas barrier property of the PVA film decreases, but on the other hand, the oxygen gas barrier property under the drying conditions inherent to the PVA film decreases. As a result, it is very difficult to obtain good oxygen gas parier properties under high humidity. In general, cross-linking of polymer molecules improves water resistance.However, gas barrier property is a property to prevent penetration and diffusion of relatively small molecules such as oxygen, and gas barrier property can be obtained by simply cross-linking polymer. For example, three-dimensional crosslinkable polymers such as epoxy resins and phenolic resins do not have gas barrier properties. Further, an invention has been proposed in which a gas barrier laminate is manufactured by heat treatment at a lower temperature or for a shorter time than before using PVA and a maleic acid-based copolymer (Reference 8: Japanese Patent Application Laid-Open No. 2001-323204, Reference 9: JP-A-2002-020677, Reference 10: JP-A-2002-241671).

 The inventions disclosed in References 8 to 10 provide a gas barrier laminate under milder conditions than the inventions disclosed in References 1 to 7. However, further improvements in the obtained gas barrier properties were desired. Disclosure of the invention

 According to a first aspect of the present invention, a plastic substrate, a gas barrier layer formed from a coating material for forming a gas barrier layer containing polyvinyl alcohol and an ethylene-maleic acid copolymer, Producing a laminate comprising: a polymer layer containing a compound, wherein the polymer layer is laminated on at least one surface of the gas barrier layer; and heat treating the obtained laminate in the presence of water. A method for producing a gas barrier laminate including the above is provided.

 According to a second aspect of the present invention, a gas filter containing polyvinyl alcohol and an ethylene-maleic acid copolymer directly on a plastic substrate or on a plastic substrate via an undercoat layer. Applying a layer forming paint and heat-treating; and heat-treating the obtained laminate in the presence of water containing a metal compound of a divalent or higher valent metal. A manufacturing method is provided. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view schematically showing one embodiment of the gas barrier laminate. FIG. 2 is a cross-sectional view schematically showing another embodiment of the gas-pares laminated body. FIG. 3 is a cross-sectional view schematically showing another embodiment of the gas-pares laminated body. FIG. 4 is a cross-sectional view schematically showing still another embodiment of the gas barrier laminate. BEST MODE FOR CARRYING OUT THE INVENTION

 The first method for producing a gas barrier laminate according to the present invention includes a step of producing a laminate including a plastic substrate, a gas barrier layer, and a polymer layer; Obtaining a gas barrier laminate. The laminate (or the gas barrier laminate after the heat treatment) 10 has, for example, a configuration in which a plastic substrate 1, a polymer layer 3, and a gas barrier layer 2 are laminated in this order, as shown in FIG. Have. Alternatively, as shown in FIG. 2, a configuration may be adopted in which a plastic substrate 1, a gas barrier layer 2, and a polymer layer 3 are laminated in this order. That is, the polymer layer 3 only needs to be laminated on at least one surface of the gas barrier layer 2. As shown in FIG. 1, when the polymer layer 3 is located between the plastic substrate 1 and the gas barrier layer 2, the polymer layer 3 is also called an under-coat layer (or a UC layer 31). As shown in FIG. 2, when the polymer layer 3 is located on the non-substrate surface of the gas ply layer 2, the polymer layer 3 is also called an overcoat layer (or an OC layer 32). Further, as shown in FIG. 3, the laminate 10 includes a plastic substrate 1, a first polymer layer (UC layer) 31, a gas barrier layer 2, and a second polymer layer (OC layer) 3. 2 may be stacked in this order.

As described later, the polymer layer 3 in the laminated body 10 is a layer containing a metal compound of a divalent or higher valent metal, but as shown in FIG. In such a case, the metal compound of a divalent or higher valent metal may be contained in a plurality of layers thereof, or may be contained in any one of the layers. In other words, plastic substrate 1 UC layer containing metal compound 3 1 Gas barrier layer 2 / gold An OC layer 32 containing no metal compound or a plastic substrate 1 a UC layer 31 containing no metal compound / a Z gas barrier layer 2 / an OC layer 32 containing a metal compound can also be used.

 A second method for producing a gas barrier laminate according to the present invention comprises a step of applying a gas-paria layer-forming paint directly or via a UC layer on a plastic base material and heat-treating to form a gas barrier layer. And a step of subjecting the obtained laminate to a heat treatment in the presence of water containing a metal compound of a divalent or higher valent metal to obtain a gas barrier laminate. In this case, the configuration of the laminate (or the gas barrier laminate after the heat treatment) 20 includes a plastic substrate 1 and a gas barrier layer 2 and does not include a polymer layer 3, as shown in FIG. Alternatively, as shown in FIGS. 1 to 3, the configuration may include a UC layer 3 (31) and a Z or OC layer 3 (32). However, even when a polymer layer is included, a metal compound of a divalent or higher valent metal is not an essential component of the polymer layer (it may be included).

In the first aspect of the present invention, there is provided a laminated body 10 in which a polymer layer containing a metal compound of a divalent or higher valent metal is essential, and in the second aspect of the present invention, a metal compound of a divalent or higher valent metal is included. The laminate 20 in which the polymer layer is not an essential component may have a configuration in which another plastic film or another polymer layer is further laminated on each of the above-described configurations. For example, although not shown in the attached drawings, a layer made of an arbitrary polymer may be further formed on the plastic base material on which the gas barrier layer and the like are not formed, An arbitrary layer other than the UC layer may be formed between the plastic substrate and the base material. At that time, in the first present invention, the UC layer and the C layer should be in direct contact with the gas barrier layer so that the metal compound (E) in the UC layer and the OC layer can easily migrate to the gas barrier layer. preferable. However, as long as the layer does not hinder the permeation and action of the metal compound, it can be provided between the UC layer and the gas barrier layer and between the gas barrier layer and the OC layer. Also in the second invention, it is preferable that the arbitrary polymer layer is a layer which does not hinder the permeation and action of the metal compound in the treated water into the gas barrier layer. As described below, the laminates 10 and 20 are coated with a paint (composition) for forming each layer by a mouth-coating method, a gravure method, a gravure offset method, a spray coating method, or any of them. It can be manufactured by coating to a desired thickness on the plastic substrate 1, the UC layer 31 or the gas barrier layer 2, respectively, by a method combining these methods, but the method is not limited to these methods. Absent.

(1) Plastic substrate

 The plastic substrate 1 of the laminate 10 or 20 may be a film-like substrate produced from a thermoformable thermoplastic resin by means such as extrusion molding, injection molding, blow molding, stretch blow molding or drawing. In addition, base materials having various container shapes such as bottles, cups, and trays can be used. Among them, a film-like base is preferable, and one having excellent transparency is preferable. When a packaging material is made of a gas barrier laminate using a highly transparent plastic substrate, the inside of the packaging material can be seen from the outside.

 The plastic substrate may be composed of a single layer or may be composed of multiple layers, for example, by co-extrusion or other lamination.

 An unstretched film is used as a plastic substrate, and a coating for forming a gas barrier layer or a coating for forming a UC layer (composition for UC), which will be described later, is applied, dried, and then stretched. For example, after drying, the film can be fed to a ten-stretch stretching machine to stretch the film simultaneously in the running direction and the width direction (simultaneous biaxial stretching) and heat-treated. Alternatively, the film is stretched in the running direction of the film using a multi-stage heat roll or the like, then a coating material for forming a gas barrier layer is applied, dried, and then stretched in the width direction by a tenter-type stretching machine (sequential biaxial stretching). Good. It is also possible to combine the stretching in the running direction and the simultaneous biaxial stretching in the same time.

The thermoplastic resins that make up the plastic substrate include olefin copolymers, polyesters, polyamides, styrene copolymers, vinyl chloride copolymers, and Examples include ril-based copolymers and polycarbonates, and preferred are olefin-based copolymers, polyesters and polyamides.

 Olefin copolymers include low-, medium- or high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ionomer, ethylene-vinyl acetate copolymer. Coalescence, ethylene-vinyl alcohol copolymer, etc .; Polyester: polyethylene terephthalate (PET), polybutylene terephthalate, PETZ isophthalate, polyethylene naphthalate, etc .; Polyamide: nylon 6, nylon 6 Styrene copolymers such as polystyrene, styrene-butadiene block copolymer, styrene-acrylonitrile copolymer, and styrene-butadiene-acrylonitrile. Polymer (ABS Jusuki), etc .; Vinyl chloride-based copolymers include polyvinyl chloride and vinyl chloride-vinyl acetate copolymer; acrylic copolymers include polymethyl methacrylate and methyl methacrylate-ethyl acrylate copolymer; Respectively. These thermoplastic resins may be used alone or in combination of two or more.

The thermoplastic resin may contain, if desired, one or more additives such as pigments, antioxidants, antistatic agents, ultraviolet absorbers, and lubricants in a total amount per 100 parts by weight of the resin. It can be added in the range of 0.001 to 5.0 parts by weight. In order to secure the strength of the packaging material when forming the packaging material as described later using the gas barrier laminate obtained by the present invention, various reinforcing materials are used as a plastic base material constituting the gas barrier laminate. Can be used. Fiber reinforced materials such as glass fiber, aromatic polyamide fiber, carbon fiber, pulp, and cotton and phosphorus; powder reinforcing materials such as power pump racks and white carbon; or flakes such as glass flakes and aluminum flakes One or two or more of the reinforcing members may be blended in a total amount of 2 to 50 parts by weight per 100 parts by weight of the thermoplastic resin. One or more of heavy or soft calcium carbonate, mica, talc, kaolin, gypsum, clay, barium sulfate, alumina powder, silica powder, magnesium carbonate, etc. 0 0 5-10 as total amount per weight part

In an amount of 0 parts by weight, it can be blended according to a known formulation.

 Further, in order to improve gas barrier properties, scaly inorganic fine powders such as water-swellable mica and clay are used in a total amount of 100 to 100 parts by weight of the thermoplastic resin.

It may be added in an amount of 0 parts by weight according to a known formulation.

(2) Gas barrier layer

 The gas barrier layer 2 (or D) of the laminate 10 or 20 is formed by the gas barrier layer forming paint (C). The coating material (C) for forming a gas barrier layer is for applying a gas barrier property to the above-mentioned plastic base material and the like, and is composed of PVA (A) and an ethylene-maleic acid copolymer (hereinafter referred to as “EMA”). (B).

 <P VA (A)>

 The polyvinyl alcohol (A) can be obtained by a known method such as complete or partial genification of a vinyl ester polymer (or a copolymer of a pinyl ester and another vinyl aldehyde compound described later).

 Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate. Of these, vinyl acetate is the most industrially preferred.

As long as the effects of the present invention are not impaired, other vinyl compounds (vinyl / based monomers) can be copolymerized with the beer ester. Other vinyl monomers include crotonic acid, acrylic acid, methacrylic acid and other unsaturated monocarboxylic acids and their esters, salts, 'anhydrides, amides, nitriles; maleic acid, itaconic acid, fumaric acid, etc. Unsaturated dicarboxylic acids and salts thereof; α-olefins having 2 to 30 carbon atoms; alkyl bier ethers; vinylpyrrolidones and the like. Gasba The polymer contained in the rear layer forming paint (C) is preferably water-soluble for production. Therefore, the hydrophobic copolymer component is contained within a range that does not impair the water-solubility of PVA (A). It is preferred that

 As a saponification method of the vinyl ester (co) polymer, a known alkali saponification method or acid saponification method can be used. Among them, alcohol hydrolysis is carried out using methanol in methanol. The method is preferred. The degree of genification is preferably closer to 100% from the viewpoint of gas barrier properties. If the degree of saponification is too low, the barrier performance decreases. Usually, the degree of saponification is preferably about 95% or more, more preferably 98% or more.

 The average degree of polymerization of PVA (A) is preferably from 50 to 4,000, more preferably from 200 to 3,000.

<EMA (B)>

 The ethylene-maleic acid copolymer (B) is obtained by polymerizing maleic anhydride and ethylene by a known method such as solution radical polymerization. In addition, other vinyl compounds can be copolymerized in a small amount as long as the object of the present invention is not impaired. Other Bier compounds include, for example, acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and the like; vinyl esters such as vinyl formate and vinyl acetate And olefins having 3 to 30 carbon atoms, such as propylene and isobutylene; and compounds having a reactive group that reacts with a hydroxyl group of PVA.

 The maleic acid unit in EMA (B) is preferably at least 10 mol%, and an alternating copolymer of ethylene and maleic anhydride having approximately equimolar maleic acid units is preferable. If the amount of the maleic acid unit is less than 10 mol%, the formation of a crosslinked structure by the reaction with the PVA unit is insufficient, and the gas barrier property may be reduced.

The weight average molecular weight of EMA (B) is preferably from 3,000 to 1,000,000 (million), more preferably from 5,000 to 900,000. More preferably, it is 10 0, 00 0 to 800, 0 00.

 In the EMA (B), the maleic acid unit easily becomes a maleic anhydride structure in which a neighboring lipoxyl group is dehydrated and cyclized in a dry state, and opens into a maleic acid structure when wet or in an aqueous solution. The paint (C) for forming a gas barrier layer contains the above PVA (A) and EMA (B) in a weight ratio of (A): (B) = 90: 10 to: 10: 90. Is preferred, 70: 30 to 15: 85 is more preferred, 60: 40 to 20: 80 is still more preferred, and 50: 50 to 25: 75 is particularly preferred. If either PVA (A) or EMA (B) is relatively high, the effect of improving the barrier properties may be reduced even if heat treatment is performed in the presence of water.

 PVA (A) and EMA (B) may each contain two or more types, and in that case, it is only necessary that the respective total amounts have the above-mentioned weight ratio. The coating material (C) may further contain an inorganic layered compound. By containing the inorganic layered compound, the gas barrier property of the gas barrier layer / gas barrier property laminate can be further improved.

 From the viewpoint of gasparity, it is preferable that the content of the inorganic layered compound is large. However, inorganic layered compounds have a strong affinity for water and are easily wetted. In addition, paint containing an inorganic layered compound tends to have a high viscosity, so that paintability is easily impaired. Further, when the content of the inorganic layered compound is large, the transparency of the formed gas barrier layer / gas barrier laminate may be reduced.

 Therefore, from these viewpoints, the inorganic layered compound is preferably used in an amount of 1 to 300 parts by weight based on a total of 100 parts by weight of PVA (A) and EMA (B), The amount is more preferably 100 parts by weight, and even more preferably at most 100 parts by weight.

The term “inorganic layered compound” as used herein refers to a compound in which unit crystal layers overlap to form a layered structure. Preferred are organic compounds that swell and cleave in a solvent.

 Preferred examples of the inorganic layered compound include montmorillonite, nofdelite, saponite, hectorite, sauconite, vermiculite, fluoromica, muscovite, paragonite, phlogopite, biotite, lepidolite, margarite, clintnite, and anandite. , Chlorite, dombasite, sudite, coucheite, clinochlore, shamosite, omite, tetrasilyl myeite, talc, pyrophyllite, nacryite, kaolinite, halosite, chrysotile, sodium teniolite, zansofilite , Antigorite, dateskite, and hydrotalcite, with swellable fluoromica or montmorillonite being particularly preferred.

 These inorganic layered compounds may be naturally occurring compounds, artificially synthesized or modified compounds, or those obtained by treating them with organic substances such as onium salts. Is also good.

 The swellable fluoromica-based mineral is represented by the following formula (1) and is most preferable in terms of whiteness.

(MF) · β (a M g F ₂ -b M g O) · Si i ₂ · · · (1) (In the formula (1), M represents sodium or lithium, α, β, r> a and b represent coefficients, respectively, 0.1 ≤ α ≤ 2, 2 ≤ β ≤ 3.5, 3 ≤ Ύ ≤ 4, 0 ≤ a ≤ 1, 0 ≤ b ≤ l, a + b = l .)

 As a method for producing such a swellable fluoromica-based mineral, for example, silicon oxide, magnesium oxide, and various fluorides are mixed, and the mixture is mixed in an electric furnace or a gas furnace. There is the so-called melting method, in which the melt is completely melted in the temperature range of ° C and the crystal of the fluoromica-based mineral grows in the reactor during the cooling process.

There is also a method of obtaining a swellable fluoromica-based mineral by using talc as a starting material and then injecting alkali metal ions into the solution (Japanese Patent Application Laid-Open No. 2-149419; Incorporated herein by reference). In this method, talc is mixed with an alkali silicate or an alkali fluoride, and is mixed in a magnetic rutupo with about 700- By performing heat treatment at 1200 ° C for a short time, a swellable fluoromica-based mineral can be obtained. At this time, the amount of the alkali silicate or the alkali fluoride mixed with the talc is preferably in the range of 10 to 35% by weight of the whole mixture. It is not preferable because the production yield is reduced. The alkali metal of alkali silicofluoride or alkali fluoride is preferably sodium or lithium. These alkali metals may be used alone or in combination. In addition, when potassium is used as the alkali metal, a swellable fluoromica-based mineral cannot be obtained.However, when used in combination with sodium or lithium, and in a limited amount, it is used for the purpose of adjusting the swellability. Is also possible. Further, in the step of producing the swellable fluoromica-based mineral, a small amount of alumina may be mixed to adjust the swellability of the generated swellable fluoromica-based mineral. Montmorillonite is represented by the following formula (2) and can be obtained by purifying naturally occurring products.

During _{M a S i 4 (A 1} 2 _ a Mg a) O 10 (OH) 2 · nH 2 〇 · · · (2) (Equation (2), M represents a cation of sodium, a is 0.25 The number of water molecules bonded to the ion-exchangeable cations between the layers can vary depending on conditions such as cation species and humidity, and is represented by nH _{20 in the} formula. )

 Montmorillonite also includes magnesia-montmorillonite, iron-montmorillonite, and isomorphous y-substituted iron-magnesian montmorillonite represented by the following formulas (3) to (5), and these may be used.

_{MaS i 4 (A l 67 -} !.. A Mg 0 5 + a) 〇 ₁₀ (OH) ₂ · nH ₂ 〇 · · · (3) Ma S i 4 (F e 2 _ a 3+ Mg a) 〇 ₁₀ (OH) ₂ · nH ₂ 〇 · · · (4) MaS i 4 (Fe x. 67 _ a 3+ Mg 0. 5 + a) O 10 (OH) 2 · ηΗ 2 0 · · (5) ( In the formulas (3) to (5), Μ represents a sodium cation, and a is 0.25 to 0.60.)

Normally, montmorillonite has ion-exchangeable cations such as sodium and calcium between its layers, but the content ratio varies depending on the producing area. Above all, Ion It is preferable to use montmorillonite in which the ion-exchangeable cation between layers is replaced with sodium by an exchange treatment or the like. It is preferable to use montmorillonite purified by water treatment.

 The inorganic layered compound can be directly mixed with PVA (A) and EMA (B), but is preferably swelled and dispersed in a liquid medium before mixing. The liquid medium for swelling and dispersing is not particularly limited.For example, in the case of a natural swelling clay mineral, water, methanol, ethanol, propanol, isopropanol, alcohols such as ethylene glycol and diethylene glycol, and dimethylformamide , Dimethyl sulfoxide, acetone and the like, and alcohols such as water and methanol are more preferable.

 The paint (C) further includes a heat stabilizer, an antioxidant, a reinforcing material, a pigment, a deterioration inhibitor, a weathering agent, a flame retardant, a plasticizer, a release agent, and a lubricant, as long as the properties are not significantly impaired. One or more kinds of agents may be added.

 Examples of the heat stabilizer, antioxidant and deterioration inhibitor include hindered phenols, phosphorus compounds, hindered amines, thio compounds, copper compounds, alkali metal halides, and mixtures thereof.

The concentration of the paint (C) (that is, the solid content) can be changed as appropriate depending on the specifications of the coating equipment and the drying / heating equipment. However, if the solution is too dilute, a layer having a sufficient thickness to exhibit gas barrier properties is used. This makes it difficult to coat the film, and the subsequent drying step tends to take a long time. On the other hand, if the concentration of the paint (C) is too high, it is difficult to obtain a uniform paint, which tends to cause problems in paintability. From such a viewpoint, the concentration (solid content) of the paint (C) is generally preferably in the range of 5 to 50% by weight. The gas barrier layer 2 is formed by applying a coating (C) for forming a gas barrier layer containing the above-mentioned PVA (A) and EMA (B) onto the plastic substrate 1 or the UC layer 31 and subjecting it to heat treatment. Is done. With this heating, PVA (A) and EMA (B) This causes an esterification reaction with PVA (A) and an etherification reaction between PVA (A), resulting in a gas barrier layer with excellent water resistance. In other words, once the coating (C) is applied, it is subjected to heat treatment once, causing an esterification reaction between PVA (A) and EMA (B), etc., and the final gas barrier layer obtained by the hydrothermal treatment described below. A gas barrier layer, which may be called a precursor, is formed.

 The preferable heat treatment conditions for the coating (C) when forming the gas barrier layer 2 can be influenced by the ratio of PVA (A) and EMA (B) in the coating (C). However, it is preferable to carry out at a temperature of 100 ° C or more and 300 ° C or less, more preferably 120 ° C or more and 250 ° C or less, more preferably 140 ° C or more and 240 ° C. The following is more preferable. The temperature is more preferably from 160 ° C to 220 ° C.

 For details, at least 90 seconds in the temperature range of 100 ° C or more and less than 140 ° C, or 1 minute or more in the temperature range of 140 ° C or more and less than 180 ° C, or 180 ° C It is preferable to perform heat treatment for 30 seconds or more in a temperature range of not less than C and less than 250 ° C; for more than 2 minutes in a temperature range of 100 ° C or more and less than 140 ° C, or 140 ° C More preferably, heat treatment is performed for 90 seconds or more in a temperature range of C or more and less than 180 ° C, or for 1 minute or more in a temperature range of 180 or more and 240 ° C or more; 4 minutes or more in the temperature range of 140 ° C or less, or 3 minutes or more in the temperature range of 140 ° C or more and less than 180 ° C, or the temperature range of 180 ° C or less and 220 ° C or less It is particularly preferable to perform the heat treatment for about 2 minutes.

 If the temperature of the heat treatment is too low or the time is too short, the esterification reaction becomes insufficient, and the water resistance of the gas barrier layer 2 or the gas barrier laminate 10 or 20 may be insufficient. On the other hand, when the heat treatment is performed at a temperature exceeding 300 ° C., the formed gas barrier layer and the plastic base material are deformed, wrinkled, thermally decomposed, and the like, and as a result, physical properties such as gas barrier properties are easily reduced.

Regarding the heat treatment time, the longer the treatment time, the higher the gas barrier properties under high humidity tend to be.However, considering the productivity and the deformation and deterioration of the plastic substrate due to heat, the treatment time is within 1 hour It is more preferably within 30 minutes, particularly preferably within 20 minutes. The thickness of the gas barrier layer is preferably greater than 0.1 m in order to sufficiently enhance the gas barrier properties of the laminate.

(3) Polymer layer (UC layer, OC layer)

 The polymer layer 3 (or F) of the laminate 10 (the first present invention) contains a metal compound (E) of a divalent or higher-valent metal. As described above, this metal compound (E) may be contained in any of the UC layer (or F 1) and the OC layer (or F 2) as the polymer layer 3. When both layers of C layer 32 are formed (see FIG. 3), they may be included in both layers, or may be included in either one of the layers. In the second aspect of the present invention, the metal compound (E) is contained in water for treating the laminate 20 (described later).

<Metal compound (E)>

 The metal compound (E) is a metal compound of a divalent or higher valent metal (also referred to as a divalent or higher valent metal compound). Preferably, it is one that can react with a hydroxyl group or a hydroxyl group. As described later, water acts on the formed gas-barrier laminate 10 or 20, and the metal compound (E) transferred to the gas-barrier layer 2 reacts with 7] <acid group or carboxyl group. It is considered that a crosslinked structure is suitably formed. The cross-linking structure generated here may be a coordination bond as well as an ionic bond or a covalent bond. It is necessary for the metal compound (E) to move from the polymer layer (first invention) or the treated water (second invention) to the gas barrier layer by the action of water. It is preferable to have high affinity, and it is preferable to have water affinity, that is, water-soluble. However, even those generally referred to as poorly water-soluble or water-insoluble can be sufficiently used by controlling the working conditions of water.

Examples of the metal compound (E) capable of reacting with a hydroxyl group or a hydroxyl group include a halide, hydroxide, oxide, carbonate, acetate, phosphate, phosphite, Hypophosphite, sulfate, hydrochloride, nitrate, or sulfite (E 1); Jill Conium complex salts, zirconium halides, zirconium salts of inorganic acids or zirconium salts of organic acids (E2) and the like are preferred, and metal compounds (E1) are preferred. Among the metal compounds (E 1), among the hydroxides, oxides, carbonates, acetates, phosphates, phosphites, hypophosphites, sulfates, hydrochlorides of divalent or higher valent metals Or a nitrate, more preferably one or more selected from the group consisting of hydroxide, carbonate, acetate and phosphate, and one or more hydroxides or Is particularly preferably a carbonate.

 As the divalent or higher valent metal, Mg, Ca, Zn, Cu, Co, Fe, Ni, A1 or Zr are preferred, Mg and Ca are more preferred, and Mg is even more preferred.

 As the metal compound (E) of a divalent or higher valent metal, one selected from the group consisting of E1 and E2 may be used alone, or within the group consisting of either E1 or E2. Can be used in combination, or one or more selected from each group of E1 and E2 can be used in combination.

Metal compound and more particularly for (E 1), as for example Mg compounds, MgO, Mg (〇_H) _2, MgS_〇 _4, MgC 1 _2, MgC_〇 _3, Mg (CH ₃ C_〇_〇_H) ₂ , Mg ₃ (P_rei_4) _2. Examples of the C a _{compound, CaO, Ca (OH) 2} , CaS 0 4, C a C 12, CaC0 3, C a (CH 3 C_〇_OH) ₂ , C a ₃ (P〇2, etc.).

Examples of the metal compound (E2) include zirconium chloride, zirconium hydroxychloride, zirconium tetrachloride, zirconium bromide, and the like; zirconium salts of mineral acids such as zirconium sulfate, basic zirconium sulfate, and zirconium nitrate. Organic zirconium salts such as zirconium formate, zirconium acetate, zirconium propionate, zirconium caprylate, zirconium stearate; ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, sodium zirconium oxalate; Zirconium complex salts such as zirconium sodium citrate and zirconium ammonium citrate are mentioned, and among them, zirconium carbonate ammonium is preferable. As a commercially available zirconium carbonate ammonium, “Zircosol AC-7” manufactured by Nutex Co., Ltd. may be mentioned.

In the first aspect of the present invention, when the metal compound (E) is contained in the polymer layer 3 of the laminate 10, MgO, Mg (OH) _2, and Mg compounds such MgS_〇 _4, CaO, C a (OH ) ₂ , C a compounds such as C a S〇4 are particularly preferred.

If the second aspect of the present invention, the water to heat treating the laminate 20 metal compound (E) is containing _{Yu, Mg (OH) 2, MgC0} 3, Mg (CH 3 CO_〇_H) _2, Mg ₃ (P04) Mg compound such as _{2 or, Ca (OH) 2, CaC0} 3, C a (CH 3 _{CO_〇_H) 2, Ca 3 (PO 4} ) C a compound is particularly preferred, such as _2, Mg (〇_H ) _2, MgC0 _3, Ca (〇_H) _2, C a C0 ₃ is more preferred. As the metal compound contained in the water to heat treating the laminate _{20, Mg (OH) 2,} MgC0 3, Ca (OH) 2, if used CaC_〇 _3, may be used only these compounds, these Since the compound of the formula (1) has low solubility in water, it may be used in combination with other metal compounds, for example, sulfates, hydrochlorides, nitrates and the like such as Mg, Ca and Na.

 When either the UC layer or the OC layer of the laminate 10 contains the metal compound (E), the above metal is used with respect to 100 parts by weight of the polymer component of the paint (composition) for forming the UC layer or the OC layer. The compound is preferably contained in an amount of from 0.2 to 40 parts by weight, more preferably from 0.3 to 20 parts by weight, even more preferably from 0.5 to 10 parts by weight.

 When the water for heat-treating the laminate 20 contains the metal compound (E), the metal compound is preferably contained in a concentration of 3 to 3000 ppm as a metal ion concentration, and preferably 10 to 500 ppm. , More preferably 20 to 300 ppm, and most preferably 30 to 200 ppm. More specifically, in the laminate lm2, it is preferable that Mg and Ca are contained in the water in an amount of 0.008 g or more, more preferably 0.08 g or more, and 0.8 or more. More preferably, it is contained in an amount of g or more.

Further, as a counter ion of a divalent or higher valent metal in water for heat treatment of the laminate 20, Preferably, carbonate ion is contained in an amount of at least 0.008 g, more preferably at least 0.08 g, and even more preferably at least 0.8 g. When the polymer layer 3 is the UC layer 31, the UC layer is located between the gas barrier layer 2 and the plastic substrate 1, and mainly plays a role of improving the adhesion of the gas barrier layer 2.

 As the polymer for the UC layer, various polymers such as urethane-based, polyester-based, acryl-based, and epoxy-based polymers can be used, and a polyurethane-based polymer is preferable.

 In the case of a urethane-based UC layer, for example, a plastic substrate 1

A gas barrier laminate comprising / UC layer 31 / gas barrier layer 2 can be obtained.

 (i) A UC composition containing a polyol component such as polyester polyol ゃ polyether polyol and a polyisocyanate component is coated on a plastic substrate and heated to react the polyol component with the polyisocyanate component. In this way, a perennial UC layer is formed. The solution of the coating material (C) is applied on the obtained UC layer, and heated to form a gas barrier layer on the UC layer.

 (ii) The same UC composition as above (i) is coated on a plastic substrate and dried, and the precursor of the UC layer, in which the reaction between the polyol component and the polyisocyanate component is not completed, is obtained. Then, a solution of the coating material (C) is applied on the precursor and heated to thereby form the UC layer and the gas barrier layer at a time.

 (iii) The same UC composition as above (i) is applied onto a plastic substrate, and then the above coating material (C) is applied without heating, followed by heating to form a UC layer and form a gas barrier layer. And forming at once.

The polyisocyanate contained in the composition for UC also reacts with the hydroxyl group in PVA (A) in the interface region with the gas barrier layer, thereby contributing to the improvement of adhesion and assisting the cross-linking of the gas barrier layer. The methods (ii) and (iii) are preferable because they are considered to be effective for improvement. As the polyol component used for the formation of the uc layer, a polyester polyol is preferable. As the polyester polyol, a polycarboxylic acid or a dialkyl ester thereof or a mixture thereof is reacted with a glycol or a mixture thereof. Obtained by the above method. Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as isophthalic acid, terephthalic acid, and naphthalene dicarboxylic acid; and aliphatic polycarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and cyclohexanedicarboxylic acid. Acids. Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyldaricol, and 1,6-hexanediol.

 These polyester polyols preferably have a glass transition temperature (hereinafter referred to as “Tg”) of 50 ° C to 120 ° C, more preferably −20 to 100 ° C, and 0 ° C. A temperature of ~ 90 ° C is more preferred. The preferred Tg of the polyester polyol is also related to the heat-curing conditions when heat-curing after the application of the gas barrier layer forming paint (C). If the coating (C) is to be cured by heating at a relatively low temperature, a polyester polyol having a relatively high Tg is preferred.If the coating is to be cured by heating at a relatively high temperature, a polyester polyol having a relatively wide Tg from low to high temperatures is preferred. It can be used preferably. For example, when the coating material (C) is cured by heating at 180 ° C, a polyester polyol having a Tg of about 70 to 90 ° C is preferable. On the other hand, when the paint (C) is cured by heating at 200 ° C, a polyester polyol having a Tg of about 0 to 90 ° C can be used.

 The number average molecular weight of these polyester polyols is preferably from 1,000 to 100,000 (100,000), more preferably from 3,000 to 50,000, and from 10,000 to 40,000. Is more preferred.

Examples of the polyisocyanate used for forming the UC layer include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, and p-phenylene diisocyanate. Isocyanate, 4,4,1-diphenylmethanediisocyanate, 2,4'-diphenylmethanediisocyanate, 2,2 ' —Diphenylmethane diisocyanate, 3, 3 ′ —Dimethyl-4,4, -biphenylene diisocyanate, 3,3 ′ Dimethoxy-4,4 ′ —Biphenylene dithiocyanate, 3,3,1-Dichloro-4,4 ,-Bi-Fen

Aromatic polyisocyanates such as nitrates; tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trinate, 1,4-cyclohexylene diisocyanate Aliphatic polyisocyanates, such as hydrogenated xylylenediocyanate, lysine diisocyanate, isophorone diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate; Polyisocyanate compounds such as isocyanurate, burette, and arophanate derived from the monomer; or terminal isocyanate groups obtained by reaction with trifunctional or higher-functional polyol compounds such as trimethylolpropane and glycerin. Contained polyfunctional polysocyanate compounds, etc.Trifunctional isocyanurate, a trimer of hexamethylene diisocyanate, is preferred.

 The weight ratio of the polyester polyol to the polyisocyanate is preferably 10:90 to 99: 1, more preferably 30:70 to 90:10, and 50:50. ~ 85: 15 are more preferred.

 The thickness of the UC layer can be appropriately determined according to the intended use, but is preferably from 0.1 to 10 m, more preferably from 0.1 to 5 m, It is particularly preferred that the thickness is 0.1 to 1 m. When the thickness is less than 0.1 μπι, it is difficult to exhibit adhesiveness. On the other hand, when the thickness exceeds 10 m, difficulty tends to occur in production processes such as coating.

The concentration of the polyester polyol and polyisocyanate in the UC composition The concentration can be adjusted using a suitable solvent, and the concentration thereof is preferably in the range of 0.5 to 80% by weight, more preferably 1 to 70% by weight. If the concentration of the solution is too low, it becomes difficult to form a coating film having a required thickness, and an excessive amount of heat is required during drying, which is not preferable. On the other hand, if the concentration of the solution is too high, the viscosity of the solution becomes too high, which may lead to poor operability during mixing and coating.

 Solvents that can be used in the composition for UC include, for example, toluene, MEK (methylethyl ketone), cyclohexanone, solvent naphtha, isophorone, xylene, MIBK (methyl isobutyl ketone), ethyl acetate, and butyl acetate. It is not limited to these.

 In the UC layer, in addition to the above components, curing accelerator catalyst, filler, softener, antioxidant, stabilizer, adhesion promoter, leveling agent, defoamer, plasticizer, inorganic filler, tackifier One or more known additives such as resins, fibers, coloring agents such as pigments, and working time extenders can also be used. Next, the OC layer 32 will be described. The OC layer can be formed by various materials and various methods as in the case of the UC layer. An example is shown below.

 (i) A solution of paint (C) is applied on a plastic substrate or UC layer and heated to form a gas barrier layer 2 in which PVA (A) and EMA (B) have reacted. 2) Apply a coating for forming layer C (composition for OC) on top and heat to form layer C.

 (ii) A solution of the paint (C) is applied on the plastic substrate or the UC layer, dried, and the reaction between PVA (A) and EMA (B) is not completed. Then, a composition for 塗 C is applied on the paint layer and heated, and the reaction between PV A (A) and EMA (B) and the formation of the OC layer are simultaneously performed.

(iii) Apply the solution of paint (C) on the plastic substrate or UC layer, apply the OC composition without drying and heat it, and react PVA (A) with EMA (B). and The oc layer is formed simultaneously.

 Like the UC layer, the OC layer preferably has a thickness of 0.1 to 10 m, more preferably 0.1 to 5 m, and 0.1 to 2.5 m. It is particularly preferred that the thickness is ΠΙ.

(4) Heat treatment of laminate in the presence of water (hydrothermal treatment)

 The laminate obtained as described above is heat-treated in the presence of water in the first invention, and water (metal compound (E) containing the metal compound (E) in the second invention. 2) Heat treatment in the presence of Thereby, in either case, a gas barrier laminate having significantly improved gas barrier properties can be obtained. In the first present invention, the laminate 10 may be subjected to a heat treatment in the presence of the water containing the metal compound (E). In the following description, the heat treatment in the presence of water is also referred to as “hydrothermal treatment”. As a method of introducing the metal compound (E) into the gas barrier layer, there is also a method of forming a gas barrier layer using a coating material for forming a gas barrier layer containing the metal compound (E). After that, a method of introducing a metal compound (E) from the outside into the gas barrier layer is used. That is, the first invention utilizes the metal compound (E) in the polymer layer adjacent to the gas barrier layer, and the second invention utilizes the metal compound (E) in the treated water. is there. Therefore, in the present invention, the gas barrier layer forming paint (C) does not need to contain the metal compound (E), but may contain the metal compound (E).

Up to now, by heating after applying the paint, the hydroxyl group in PVA and the CO〇H in polyacrylic acid etc. can be sufficiently esterified and / or the functional group and the metal can be cross-linked. Was thought to require higher temperatures or longer times of heating. However, there are practical limits to improving the gas barrier properties under high humidity by introducing various types of cross-linking structures by heat, from the viewpoint of the heat resistance of the plastic substrate itself and the gas barrier layer being formed. However, even if the heating conditions are higher and longer, the oxygen permeability decreases above a certain value. Instead, the reversal phenomenon that it became rather large occurred.

 On the other hand, the detailed mechanism of why the gas-paring property is improved is still unknown, but as mentioned above, the gas barrier layer formed by heat-treating the paint (C) is heated while the metal is heated in the presence of water. By introducing the compound (E), it is possible to obtain a gas barrier laminate having a much better gas barrier property than before without causing thermal deterioration of the plastic substrate itself and the gas barrier layer. By hydrothermally treating the gas barrier laminate, the metal compound (E) migrates from the polymer layer into the adjacent gas barrier layer or from water into the gas barrier layer, resulting in PVA (A) and PVA (A). A dense structure is formed by cross-linking VA (A), P VA (A) and EMA (B), and EMA (B) and EMA (B), respectively, resulting in high humidity. It is considered that the oxygen gas barrier property at the bottom could be improved. Therefore, in the present invention, the metal compound (E) may be referred to as a metal crosslinking agent or simply as a crosslinking agent. The metal compound (E) preferably migrates uniformly in the thickness direction of the gas barrier layer and contributes to crosslinking, but may have a concentration distribution.

 The UC layer and the 〇C layer do not themselves have the function of improving the oxygen gas barrier property under high humidity.

 As a method for treating the gas barrier laminate (laminate) 10 and 20 with water, there are various methods as shown below, and these methods may be combined.

 (i) Immerse the laminate in water (hot water).

 (ii) Spray water (hot water) on the laminate in mist or shower form.

 (iii) Place the laminate under high humidity.

 (iv) exposing the laminate to water vapor; It may be heated with a hot roll while spraying steam.

In any of the above methods, the gas barrier laminate may be heated, the environmental temperature may be increased, or the pressure may be increased or reduced as necessary so that water acts more easily. For treatment 0, water containing the metal compound (E) may be used, and tap water in the vicinity can also be used. In addition, tap water is used for treating the laminate 10. You can also.

 The temperature of the water used for the treatment and the environmental temperature (that is, the heat treatment temperature) are preferably 90 ° C or more, more preferably 95 ° C or more, and 100 to 140 ° C. More preferably, it is most preferably 110 to 130 ° C. Further, the treatment time is preferably at least 1 minute, more preferably at least 10 minutes, and most preferably at least 20 minutes. It is preferable that the water temperature and environmental temperature are higher and the treatment time is longer.However, from the viewpoints of productivity, economy, energy saving, etc. About one hour is realistic.

 As described above, by performing the hydrothermal treatment on the gas barrier laminate, it is also possible that some change may occur in the gas barrier layer itself in addition to the formation of the crosslinked structure derived from the metal compound (E), and the gas barrier property is dramatically increased. To improve.

 Although it cannot be said unconditionally because it varies depending on the treatment conditions, the hydrothermal treatment reduces the oxygen permeability under high humidity to about 1-2.1 to 162, the level before treatment. Oxygen gas barrier properties can be improved.

 For example, the oxygen permeability measured at 25 ° C and 80% relative humidity was about 25 ccm / m2-24 hatm before 4 cc · m / m2-24 h · Atm. Use this retort treatment when it is necessary to retort (sterilize) with steam under pressure after storing the food in the container (= packaging material) among the containers (packaging material) that contain the food. As a result, the performance of the gas barrier layer constituting the packaging material can be improved. That is, the gas-barrier laminates 10 and 20 were prepared, a food packaging container was formed using the same without performing a predetermined hydrothermal treatment, and after the food was accommodated, water vapor was applied under pressure to produce 120, By performing the retort treatment (sterilization treatment) for about 30 minutes, hydrothermal treatment is performed on the gaseous laminates 10 and 20 constituting the food packaging container, and the gas barrier properties thereof can be improved. In such a case, the treated water is also called “retort water”.

If the gas barrier laminate is used as a food packaging material as described above, It is preferable that the stick base material side is the food side (inside) and the gas barrier layer side is the outside. As described above, according to the present invention, by using a water-soluble polymer that does not contain chlorine in the structure, a gas-parallel laminate having a higher oxygen gas barrier property under high humidity than before can be obtained. It can be obtained under milder conditions. That is, in the present invention, the gas barrier property can be dramatically improved surprisingly by using water, which has been considered to be a major cause of the lowering of the barrier property. Further, by introducing a metal compound of a divalent or higher valent metal from the outside into a gas barrier layer formed by heating from a coating composition containing PVA (A) and EMA (B), the gas barrier properties can be further improved. Can be.

Example

 Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples.

Oxygen permeability of the gas barrier layer (P _{ii lm)} and the gas barrier layered product oxygen permeability (P _total) was determined as follows. After leaving the obtained laminated film (= gas barrier laminate) in an atmosphere of 25 ° C. and 80% RH, an oxygen permeation tester “OX_TRAN TWIN” manufactured by Modern Contro 1 was used. 25, the oxygen permeability at _{80% RH (P t. tal} ) was measured. 25t, 8 for measurement

Oxygen gas and nitrogen gas (carrier gas) humidified to 0% RH were used. The oxygen permeability (P _PET ) of the _plastic substrate was measured in the same manner. The oxygen permeability (P _film ) of the gas barrier layer was determined by the following formula.

 PET

However,

P _total (measured value): Laminated film consisting of a film layer (= gas barrier layer) formed from the gas barrier layer forming paint (C) and a PET film (= plastic substrate) Oxygen permeability of ilum (= gas-parous laminate). When having a UC layer, the oxygen permeability of a laminated film composed of a film layer, a UC layer, and a plastic substrate.

P _{fi lm} (calculated value): Oxygen permeability of the film layer formed from paint (C).

 ΡρΕτ (measured value): The oxygen permeability of the plastic substrate (PET). If having a UC layer, the oxygen permeability of the UC layer and the plastic substrate.

<Example 1> <Comparative Example 1>

 5 parts by weight of magnesium oxide was added to 100 parts by weight of polyester, and polyester (Vylon 200 (Τ867 ^), Μη = 17 000) manufactured by Toyobo Co., Ltd. dissolved in a mixed solvent of ethyl acetate. It was dispersed using. To this solution, polyisocyanate (“Sumidur 3300” manufactured by Sumitomo Chemical Co., Ltd.) was added so that the weight ratio of the polyester and the polyisocyanate was 60:40, to obtain a mixed solution. This mixed solution was mixed with a 1% by weight solution of dibutyltin laurylate, water and ethyl acetate to obtain a primer composition (= UC composition) having a solid content of about 14% by weight.

 PVA (Poval 124, manufactured by Kuraray Co., Ltd .; polyvinyl saponification degree: 98 to 99%, average polymerization degree: about 2400) was dissolved in hot water, and then cooled to room temperature to obtain a PVA aqueous solution. Separately, an EMA (weight average molecular weight 100,000) aqueous solution was prepared.

 The aqueous PVA solution and the EMA aqueous solution were mixed so that the weight ratio of PVA and EMA was as shown in Table 1, to obtain a mixed solution having a solid content of 10% by weight (= a coating for forming a gas barrier layer).

The above UC composition is coated on a biaxially stretched polyester film (PET, 12 m thick) using Barco No. 1 No. 4 and dried in an electric oven at 80/30 sec. A 0.5 m thick film (= UC layer) was formed. The above-mentioned paint for forming a gas barrier layer is applied on the obtained UC layer using a bar coater No. 6, dried at 80 ° C for 2 minutes in an electric oven, and dried and heat-treated at 200C for 2 minutes in an electric oven. To form a 2 m thick film (= gas barrier layer) Lum (= untreated laminated film) was obtained (Comparative Example 1).

 The untreated laminated film obtained in Comparative Example 1 was treated in hot water (120, 1.2 kg f / cm ^) for 30 minutes using an autoclave to obtain a laminated film (= treated laminated film). (Example 1).

 The oxygen permeability of each of the obtained laminated films and film layers was measured.

<Examples 2 to 4> <Comparative Examples 2 to 4>

 In the same manner as in Example 1 and Comparative Example 1, a coating for forming a gas barrier layer having a solid content of 10% by weight was prepared so that the weight ratio of PVA and EMA became the value shown in Table 1, and the untreated laminated film ( Comparative Examples 2 to 4) and treated laminated films (Examples 2 to 4) were produced, and the oxygen permeability was measured.

<Comparative Example 5>

 Polyisocynate (Sumidur 3300) was added to a mixed solution of polyester (Vylon 200) dissolved in a mixed solvent of ethyl acetate / MEK so that the weight ratio of polyester to polyisocynate was 60:40. Got. A 1 wt% MEK solution of dibutyltin laurylate, MEK and ethyl acetate were mixed with this mixed solution to obtain a primer composition (= UC composition) having a solid content of about 14 wt% without magnesium oxide. .

 An untreated laminated film was prepared in the same manner as in Comparative Example 1 except that this UC composition was used, and the oxygen permeability was measured. Example 5>

 A coating material for forming a gas barrier layer having a solid content of 10% by weight was prepared in the same manner as in Example 1 except that the weight ratio between PVA and EMA was set to the value shown in Table 1.

A UC layer and a gas barrier layer were formed in the same manner as in Example 1 except that the UC composition of Comparative Example 5 and the gas barrier layer-forming paint were used. A laminated film (untreated) was obtained.

 Next, the obtained untreated laminated film was treated in an aqueous solution of 100 ppm7j <magnesium oxide (120 ° (:, 1. S kg fZcms)) for 30 minutes using an autoclave to obtain a treated laminated film.

 The oxygen permeability of the obtained laminated film and film layer was measured.

<Examples 6 to 15> <Comparative Example 6>

 The hydrothermal treatment conditions for the untreated laminated film

 100 ppm aqueous solution of magnesium carbonate (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 6);

 Ρ Ο ρ ρ pm In an aqueous solution of calcium hydroxide (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 7);

 In 100 ppm aqueous calcium carbonate solution (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 8);

 100 p pm in aqueous solution of magnesium salt (120 ° C, 1.2 kg f / cm2) 3

0 minutes (Example 9);

 30 minutes in aqueous magnesium hydroxide solution (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 10);

 30 ppm in an aqueous solution of magnesium carbonate (120 ° (:, 1.2 kg fcm2) for 30 minutes (Example 11);

 30 minutes in an aqueous solution of calcium hydroxide (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 12);

 In 30 ppm calcium carbonate aqueous solution (120 ° C, 1.2 kgf / cm2) for 30 minutes (Example 13);

In an aqueous solution containing 30 ppm of chloride ion, 40 ppm of sulfate ion, 11.6 ppm of nitrate ion, 25.7 ppm of carbonate ion, 5.1 ppm of magnesium ion, 21 ppm of calcium ion and 21 ppm of sodium ion ( 120, 1. 2 kg f / cm2) Treatment for 30 minutes (Example 14);

 In an aqueous solution containing 3.8 ppm chlorine ion, 5. O ppm sulfate ion, 1.5 ppm nitrate ion, 3.2 ppm carbonate ion, 0.6 ppm magnesium ion, 2.6 ppm calcium ion, 3.4 ppm sodium ion ( 120, 1.2 kgf / cm2) for 30 minutes (Example 15);

 A treated laminated film was obtained in the same manner as in Example 5, except that the ion-exchanged water (120 ° C, 1.2 kgf / cm2) for 30 minutes (Comparative Example 6) was used. Was measured for oxygen permeability.

 Table 1 shows the values of the oxygen permeability measured in the above Examples and Comparative Examples. In Table 1, '

(1) after the hydrothermal treatment before heat treatment = processing the laminated film after the hydrothermal treatment P _{f; lm} of Z hydrothermal treatment prior to the untreated laminated film P _f i, _m;

(2) after the hydrothermal treatment Z hydrothermal treatment before (%) = (P _{ii lm} Z hydrothermal treatment prior to P _{fi lm} after the hydrothermal treatment) X 100;

(3) Change rate of hydrothermal treatment (%) = ((P _{ii lm} after hydrothermal treatment — P _{fi lm} before hydrothermal treatment)

/ P _{fi lm} before hydrothermal treatment) X 100;

The above (1), (2), and (3) in Comparative Example 1 are P _{t in} Comparative Example 1. _tal is 50, and the above (1), (2), and (3) in Examples 5 to 15 and Comparative Example 6 are values obtained by comparing Comparative Example 5 before the hydrothermal treatment. The disclosure of the present application is related to the subject matter described in Japanese Patent Application No. 2003-105897 filed on Apr. 9, 2003 and Japanese Patent Application No. 2003-289705 filed on Aug. 8, 2003. The disclosure content is incorporated herein by reference.

It should be noted that various modifications and changes may be made to the above-described embodiments without departing from the novel and advantageous features of the invention, other than those already described. Accordingly, all such modifications and changes are intended to be included within the scope of the appended claims.

 (Note) In each of the above Examples and Comparative Examples, the heat treatment of the paint (C) was performed at 200 ° C. for 2 minutes, and the thickness of the obtained gas barrier layer was 2 μm.

Claims

The scope of the claims 1. Includes a plastic substrate, a gas barrier layer formed from a paint for forming a gas barrier layer containing polyvinyl alcohol and an ethylene-maleic acid copolymer, and a polymer layer containing a metal compound of a divalent or higher-valent metal. Producing a laminate in which the polymer layer is laminated on at least one surface of the gas barrier layer; and heat-treating the obtained laminate in the presence of water. Manufacturing method.  2. The method for producing a gas barrier laminate according to claim 1, wherein the polymer layer is an undercoat layer located between the plastic substrate and the gas barrier layer.  3. Apply a gas barrier layer-forming paint containing polyvinyl alcohol and an ethylene-maleic acid copolymer directly on the plastic substrate or on the plastic substrate via the undercoat layer and heat it. A method for producing a gas barrier laminate, comprising: treating the laminate and heating the laminate in the presence of water containing a metal compound of a divalent or higher valent metal.  4. The method for producing a gas barrier laminate according to claim 2, wherein the undercoat layer is formed of a polyester polyol having a glass transition temperature of 0 ° C. or higher and polyisocyanate.  5. The method for producing a gas barrier laminate according to any one of claims 1 to 4, wherein the metal compound is capable of reacting with a hydroxyl group or a carboxyl group.  6. The gas barrier according to claim 1, wherein the metal compound contains at least one selected from the group consisting of hydroxides, carbonates, acetates, and phosphates of divalent or higher-valent metals. A method for producing a functional laminate.  7. The method for producing a gas barrier laminate according to claim 6, wherein the metal compound contains at least one of hydroxides and carbonates of divalent or higher-valent metals. 8. The method for producing a gas barrier laminate according to any one of claims 1 to 7, wherein the divalent or higher valent metal is Mg, Z, or Ca. 9. The gas barrier according to any one of claims 1 to 8, wherein the weight ratio of polyvinyl alcohol to the ethylene-maleic acid copolymer in the coating material for forming a gas barrier layer is 90:10 to 10:90. A method for producing a functional laminate.  10. The method for producing a gas barrier laminate according to any one of claims 1 to 9, wherein the heat treatment in the presence of water is performed at 90 ° C or higher.